master cylinder PRV manifold - whats it off of

[therealnovaboy]

Can anyone tell me what this is off? I think its GM looks like corsa PRV's
http://i607.photobucket.com/albums/tt160/roygrave/Red%20Corsa/IMG_0453.jpg

[Southie]

It looks ready for scrap to me lol Home-made job?

[mowgli]

i think the mk2 cavalier had them. they were definitely fitted on some early 80's gm models